Aircraft air pump



Sept. 1, 1942. R. R. CURTIS Erm.

. AIRCRAFT Ani PUMP original Filed Feb. 29, 1940 am. Nm, QN

VE ERE 2:0556@ wfZ/s eodfe fa//eff- Patented Sept. 1, 1942 AIRCRAFT AIRPUMP Russell R. Curtis, Dayton, and Theodore R. Thoren, Bedford, Ohio,asslgnors to Curtis Pump Company, Dayton, Ohio, a corporation of OhioOriginal application February 29, 1940, Serial No.

321,494. Divided and this application May 8, 1940, Serial No. 333,980

(Cl. 30S-36.2)

8 Claims.

This invention is a division of our copending application, Serial No.321,494, led February 29, 1940, and relates to air pumps and has specialreference to air pumps for aircraft. Most modern aircraft employ a,pump, usually of the rotary sliding vane type to provide air underpressure for operating de-icing equipment, and air under vacuum foroperating night instruments, etc.

Since any power pump having rotatable elements necessarily has a.rotatable shaft extending, to which the driving force is applied, thereshould preferably be provided a seal to prevent leakage from the pumpalong the outside of the shaft, and since conservation of space isimportant, it is an object of the invention to conserve space by makingthe shaft hollow, then placing the drive within the shaft and the sealwithout the shaft, within the same axial dimensions.

A rotary pump of the sliding vane type when employed under the extremeload conditions imposed in aricraft service requires lubrication whichis not only continuous but substantially perfect, for while suflicientlubricant should pass continuously thru the pump an excess amount oflubricant is undesirable.

It is therefore another object of the invention to provide a meteringsystem for admitting lubricant to the pump under pressure and in acarefully measured amount during the entire time that the pump is underrotation, the metering system being so combined with the seal as torequire no extra space in the structure.

Another object is to provide a pump structure having means wherebyit isquickly and easily disassembled into its several parts so that renewalparts may be quickly substituted and repairs readily made. l

'Ihese and other objects and advantages will become more clearlyapparent from the following.

detailed description, reference being madeto the drawing, wherein thefigure of the drawing is an axial section thru a rotary pump embodyingthe principles of the invention.

The pump selected as an illustrative embodiment of the inventioncomprises a housing 20 having a head 22 secured thereto by screws 24 andlock washers 26. The head 22 supports one of the rotor bearings andprovides a pressure tight closure for the end of the casing.

A liner 28 is press fitted in the casing and has port openings extendingthru it which communi` cate with suction and discharge ports in thecasing, but since the design of the ports has no bearing on thisinvention they are omitted from the drawing.

"touches the liner on one side, as at 32, as is usual in pumps of thistype. A hollow stub shaft 34, an integral part of the rotor body 30,carries the bearing 36 which is supported in the head 22. A longerhollow drive shaft 38, also an integral part of the rotor body, carriesthe bearing 40 supported in the housing 20.

The rotor body 30 has four circumferentially equally spaced slots 42into which two thru vanes rdi! are slidably fitted. 'Ihe two vanesarealike, one being turned end for end with respect to the other andpositioned ninety degrees rotation therefrom. The type of vane and theirnumber is selected for illustrative purposes only and is not intended asa structural limitation of the invention.

Press tted into the hollow of the rotor driving shaft 38 is the drivingplug 46 further secured against rotation in the shaft by the pin 48. Anintegral driving hub 50 on the plug is of reduced diameter and providedwith a transverse driving slot 52.

A driving spring 54 comprises, in a single piece, an endless loop formedintc the shape of a double coiled helical spring wherein one coil 58lies between the other coil 58, the lcoils being joined together atboth. ends to compose driving portions 60 and 62 passing from theoutside of one coil to the outside of the other thru their common axis.

A driving shank t4, has a hub 86 with a. transverse slot 68 therein,substantially like the slotted hub 50 of the driving plug 46. Thedriving portions 60 and 62 of the spring lie in the slots 52' and 68 andshould be fitted to the slots closely.

The outer end of the hollow rotor shaft 38 is provided withcircumferentially spaced axial notches 18 to form overload driving jawstherebetween. 'Ihe driving shank 64 has overload driving lugs I4 whichare normally located circumferentially midway in the notches 10. Whenthe pump is being driven thru the spring 54, the spring yields slightlyand the lugs 14 move slightly closer to one or the other of the edges ofthe driving jaws on the end of the shaft 38. It is, however, only underextreme overload conditions that the torsional deflection of the springis sumcient to allow the lugs 14 to engage the drivingV jaws in drivingrelation.

Arcuate grooves extend circumferentially around the driving jaws and theinterengaged lugs 'I4 respectively, and a snap ring 80 is sprung intothese grooves to hold the shank and shaft in assembled relation andagainst greater axial movement than is desired. The ring 80 ispreferably fitted quite loosely in the grooves to allow slightmisalignment of the respective axes of the shaft and shank.

One end of the ring 80 is bent over to extend into an appropriate notchin the shaft 38 (not shown), thereby compelling unitary rotation of thering and shaft and maintaining the shaft in the ring intermediate.the'notches 10.

The outer end 86 of the shank 64 is provided with external splines 88adapted to fit slidably into a corresponding internally splined openingin the end of the engine shaft. The flange 90 of the body 20 may bebolted or similarly secured to a mounting pad on the engine.

The means provided for sealing againstleakportion to the perfection ofthe contacting sur-V faces of rotatable ring |04 with non-rotatable ring94,these surfaces, in the embodiment herein age from the drive end ofthe pump comprises several non-rotative and several rotative mfem'-bers. 'I'he metal seal cap 92 is press fitted to the body 20, a metalring 94 ts the body 20 freely, and a Asynthetic rubber washer 96 isinterposed between the two parts to seal against leakage l which mightoccur around the outside of ring 94, between parts 94 and 92 and thenthru the inside of cap 92. i p

The cap 92 is counterbored to receive thesmall hub 98which is molded asan integral part of the rubber washer 96. The ring 94 is counterboredfor the small tube 00 which is press tted in the ring and extends firsttightly thru the hub 96 then slidably into a hole in the cap 92.

The ring 94 is therefore held non rotative by the tube |00, and sincethe ring fits into the body 20 more closely than it does around theshaft 38, there is no possibility of the ring swinging with the tube |00as an axis and dragging on the rotating shaft 38.

Since synthetic rubber is subject to swelling under the action of oiland subject to flow under heavy pressure, a piloting end |02 extendsfrom the ring 94 thru and beyond the inner diameter of the rubber washer96 to confine it to its allotted space.

The rotatable members of the sealing means comprise a metal ring |04, asynthetic rubber ring |06, a cup |08 and a. springvll0. The metal ring.|04 is compelled to rotate with the shaft 38 .by a pin ||2, one end ofwhich is press tted into a. hole .in the shaft and the other endslidable ina keyway`||4 in the ring. The rubber ring |06 fits over theshaft 38 closely and is conned to normalv dimensions by the cup |08, theopen side of which extends over the ring |04 but should not f'lt it tooclosely. 'Ihe springv ||0 abuts-the inner member of the bearing 40, itsexpansive force acting against the cup |08 whereby a seal is madebetween the rubber ring |06 and shaft 38 and between the rubber ring andthe metal ring I 04, all of these parts rotating at the same speed.

shown, are ground, lapped and honed to perfect mirror like planesseparately and before assembly, and are not thereafter lapped one on theother by rotative movement therebetween, but are instead lappedaccording to the well known process of producing perfect plane surfaceswhich comprises movement of the part being lapped in constantly varyingdirection with respect to the plane surface lap.

Since, in the assembly, the rings 04 and 94 are resiliently held,neither being fitted closely t0 any other part so as to be distorted, itfol- -lows .thatthe seal thus produced is substantially perfect underrotation.

, In order to cause several of the seal members above described,tolfunction also as a metering means for the pump lubricant, the end ofthe casing 20 is provided internally with an annular groove I6 to whichoil under pressure is brought thru one of the small holes ||8 or |20.'I'he hole |20 communicates with a tapped opening |22 adapted forconnection with the main oil pressure system of the engine by suitablepiping, while the hole H8 is positioned to meet a corresponding hole inthe mounting pad of the engine, the hole in the pad communicating with achamber in the engine which contains oil under pressure. A series ofadditional holes ||8 are preferably provided so that thev pump may bemounted inverted, or, turned ninety degress either direction on its axisand in either case have a hole ||8 meet the hole in the enginev mountingpad. The press fit of the cap 92 into the body 20 closes the inside ofthe groove I|6 and converts it into a pressure tight annular channel.

'is connected by a tiny metering hole |30 to the The rotatable metalring |04, being movable axially, is therefore resiliently held incontact with the nonrotatablemetal ring 94 and it is important thattheir contacting faces each be finished to a mirror like surfaee tomaintain a perfect seal under relative rotation.

Seals of this class, as customarily constructed, would have thenon-rotative ring 94 press fitted directly'into the casing 20 and would,of course, thereby eliminate the ring 96 by combining the ring 94 andcap 92 as one part.

Where, however, the non-rotative ring is press fitted into the casing,there is substantially always slight distortion o'f the press fittedring,

A small passageway |24 in cap 92 connects the annular channel ||6 to theend of the tube |00, the passageway from the other end of the tube beingprolonged by a hole |26 which extends from the end of the tube to thejoint between the nonrotative ring 94 and the rotatable ring |04.

A radial opening |28 in the rotatable ring |04 contacting surfacesbetween rings |04 and 94.

It will now be evident that there is only one joint in the sealing meanswhere there is relative rotation, land. that there is a continuoussupply of oil under pressure conveyed to this joint from channel ||6thru tube |00 and hole |26, and that while the end of the hole |26 iskept closed by the rotating surface of ring |04 for the greater portionof each revolution, a passage way for oil is nevertheless completedduring about 21/3% of each revolution thru the metering hole |30 andradial hole I 28 to the space |32 from which it finds it way thru thebearing 40 to the blades 44 and rear bearing 36.

The hole |26 is made enough larger than the tiny metering hole |30, thatshould slight variance inthe relative radial positioning of the twoholes result from inaccuracies in manufacture,

the percentage of time the oil passage is completed, and consequentlythe amount of oil mey tered will not be seriously aifected.

The advantage of the resilient whip absorbing universal drive will beobvious. When the device is inactive, the lugs Il of the drive shank 64will be midway in the notches and when under normal load only slightlyoff the midway position one way or the other depending on the directionof rotation. Under extreme overload condition, however, such as mightinjure the driving spring 54 if much further increased, the lugs 'Il ofthe drive shank will make contact with the jaws on the end of the rotorshaft 38 and there will thenceforth be a positive drive as long as suchoverload conditions prevail.

When the device is once assembled as shown in the drawing, the entirerotor, drive 'and seal, with the exception of the cap 92 may bewithdrawn from the casing 20 by merely removing the head 22, wherebyworn or damaged parts may be readily replaced or repaired.

Having described `an embodiment of our invention in which the objectshereinbefore set forth are achieved,

We claim:

1. In a pump or the like, having a casing and a rotatable shaftextending from said casing, a combined seal and lubricant meteringdevice comprising, an end closure for said casing having an opening topass said shaft freely, a resilient packing washer covering the innerface of said closure, a metal seal ring covering the inner face of saidpacking washer, a tube located intermediate the inner and outerdiameters of said seal ring extending in an axial direction from Withinsaid ring, tightly thru the packing washer and slidably into an axiallyextending opening in the end closure, a passageway to convey lubricantunder pressure connecting said axial opening to a source of supply, aconduit opening extending from the inner face of said seal ring andterminating in the opening in said tube, a second seal ring having itsouter face resting against the inner face of the iirst seal ring andhaving a small metering opening in the outer face communicating with theinside of the casing, said metering opening being so located as toregister withsaid conduit opening in said rst seal ring at eachrevolution of the shaft, means to drivably connect said second seal forrotation with said shaft but allow it to move axially thereon, a packingring against the inner face of the second of said seal rings, a metal'part against said packing ring, and resilient means pressing said metalpart against said packing ring.

2. The structure defined in claim 1 wherein the metering opening in theouter face of the second said seal ring comprises a radial holeextending froin the outer periphery of the ring inward and a tinylateral opening extending from the outer face of the ring into theradial opening, said lateral opening being located at substantially thesame distance from the pump axis as the conduit, in the rst seal ringextending from the inner face thereof to the tube opening in the firstsaid seal washer.

3. The structure dened in claim 1 wherein the said seal washer has anintegral hub on its outer face, tightly surrounding said tube andextending into a corresponding counterbore in the end closure, the tubeextending beyond the end of said hub into the end closure.

4. The structure defined in claim 3 wherein the casing is internallygrooved, the end closure is press tted into place over said groove, andthe means containing a passageway to convey lubricant under pressure tothe opening in said end closure comprises holes in the casingcommunicating with said groove, and a radial hole in the end closureconnecting the groove to said axial opening in the end closure.

5. A combined seal and lubricant metering device for pumps and the likehaving a casing and a rotatable shaft extending therefrom comprising, anend closure extending into and retained within said casing againstrotation, a ring spaced axially from said end closure, a resilientpacking washer between said end closure and said ring, registeredopenings extending axially through said ring, packing washer and saidend closures-to a source of lubricant supply, means in said openingsconnecting said ring, packing washer and end closure for maintainingsaid openings in registry, a second ring rotatable with said shaft inface engagement with said first mentioned ring, an opening in saidsecond ring extending from the face in engagement with saidrst-mentioned ring tothe inside of said casing, said opening in saidsecond ring registering with the axial opening in said rst ring at eachrevolution of said shaft, and a resilient expansive seal between saidshaft and said second ring.

6. A metering device for pumps and the like having a casing and arotatable'shaft extending therefrom comprising a tubular end closurepartially extending into and retained within said casing againstrotation, a first seal ring construction abutting the inner face of saidend closure, registered axial openings through said seal ringconstruction and a portion of said end closure for connection to alubricant source of supply, tubular means in said openings connectingsaid seal ring construction and said end closure, a second seal ringconstruction abutting the irmer face of said first seal'ringconstruction and engaging said shaft for rotation therewith, and anopening in said second seal ring construction connecting the outer facethereof and the interior of said casing, said opening in the second sealring construction registering with said opening in the first seal ringconstruction at each revolution of said shaft.

7. A seal adapted to meter lubricant to relatively movable surfaceswhich comprises a hollow casing having an internal abutment shoulder,

a-member mounted in said casing for relative rotative movementtherewith, a irst seal construction engaging the shoulder and looselyembracing sad member, said first seal construction including a resilientseal engaging the inner periphery of the casing, said abutment shoulderhaving a hole therein communicating with the outside of the casing, saidfirst seal construction'having a hole therethrough, a hollow` pinprojecting into both holes for holding the first seal constructionagainst rotation relative to the4 shoulder and for providing a lubricantpassageway, a second seal construction -carried by said member insliding sealing relation to the first seal construction, said secondseal construction having a metering hole therein communicating with theinterior of the casing and adapted to intermittently register with thelubricant pas.- sageway to meter lubricant from the exterior to theinterior of the casing.

8. A metering and sealing device adapted to meter lubricant to a bearingwhich comprises a housing having an internal abutment shoulder, abearing in said housing, a shaft mounted in said bearing for rotationrelative to the housing, a stationary seal construction surrounding saidshaft and engaging the internal abutment shoulder of the housing, arotatable seal construction `mounted on said shaft in said housing androtatable with the shaft adjacent the stationary seal construction insliding seal engagement therewith, said abutment shoulder having a. holetherein communicating with the outside of the housing, said stationaryseal construction having a hole therethrough, a hollow pin projectinginto both holes for holding the stationary seal construction againstrotation relative to the shoulder and for providing a lubricantpassageway, said rotatable seal construction having a metering holetherein communicating with the interior 'of the housing and adapted tointermittently register with the lubricant passageway to meter lubricantfrom the exterior of the housing to the bearing inthe housing.

RUSSELL R; CURTIS. THEODORE R. THOREN.

